• 설비공학논문집
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• 제18권4호
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• pp.320-327
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• 2006

Numerical analysis and experimental study are performed to investigate the effect of heat load and operating temperature on the thermal performance of several variable conductance heat pipe (VCHP) with screen meshed wick. The heat pipe is designed in 200 screen meshes, 500 mm length and 12.7 mm outer diameter tube of copper, water (4.8 g) is used as working fluid and nitrogen as non-condensible gas (NCG). Heat pipe used in this study has evaporator, condenser and adiabatic section, respectively. Analysis values and experimental data of wall temperature distribution along axial length are presented for heat transport capacity, condenser cooling water temperature change, degrees of an inclination angle and operating temperature. These analysis and experiment give the follow findings: For the same charging mass of working fluid, the operating temperature of heat pipe becomes to be high with the increasing of charging mass of NCG. When the heat flux at the evaporator section increases, the vapor pressure in the pipe rises and consequently compresses the NCG to the condenser end part and increases the active length of the condenser. From previous process, it is found out we can control the operating temperature effectively and also the analysis and experimental results are relatively coincided well.

• 설비공학논문집
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• 제16권12호
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• pp.1204-1211
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• 2004

It is difficult to apply a conventional selection guide for diffusers when the diffuser is installed in a perimeter zone, because the air diffusion performance index (ADPI) vs. throw/length (T/L) ratio curve listed in conventional guide does not consider the perimetric heating load through the walls. The objective of this study is to evaluate the effect of the perimetric heating load on the ADPI and propose a selection guide for a proper line diffuser when perimetric heating load exists. The velocity and temperature distributions and the ADPI values are obtained numerically with various heat load ratios and air flow rates. The velocity and temperature distributions and the ADPI values are analyzed by CFD in case of various heat load ratios and air flow rates. Also, ADPI was calculated by those results. The ADPI values by numerical results are compared with an existing experimental data to verify the method for the evaluation of ADPI proposed in a present study. In case of a line diffuser installed at the high side wall, the ADPI decreases according to the increases of the flow rate on every heat load ratio of the present study except 0.75. The ADPI vs. T/L ratio curves have been proposed for the heat load ratios of 0.25, 0.5, 0.75 to guarantee the comport thermal environment when diffusers are installed in perimeter zone.

• 한국수소및신에너지학회논문집
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• 제33권5호
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• pp.534-540
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• 2022

Liquid hydrogen has the best storage capacity per unit mass and is economical among storage methods for using hydrogen as fuel. As the demand for hydrogen increases, the need to develop a storage and supply system of liquid hydrogen is emphasizing. In order to liquefy hydrogen, it is necessary to pre-cool it to a maximum inversion temperature of -253℃. The Gifford-McMahon (GM) refrigerator is the most reliable and commercialized refrigerator among small-capacity cryogenic refrigerators, which can extract high-efficiency hydrogen through liquefied hydrogen production and boil of gas re-liquefaction. Therefore, in this study, the optimal conditions for liquefying gas hydrogen were sought using the GM cryocooler. The process was simulated by PRO/II under various cooling capacities of the GM refrigerator. In addition, the flow rate of hydrogen was calculated by comparing with specific refrigerator capacity depending on the pressure and flow rate of a refrigerant medium, helium. Simulations were performed to investigate the optimal values of the liquefaction flow rate and compression pressure, which aim for the peak refrigeration effect. Based on this, a liquefaction system can be selected in consideration of the cycle configuration and the performance of the refrigerator.

• Advances in nano research
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• 제12권6호
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• pp.549-566
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• 2022

Mining of ore minerals (sfalerite, cinnabar, and chalcopyrite) from the old mine has led in significant environmental effects as contamination of soils and plants and acidification of water. Also, nanoparticles (NP) have obtained global importance because of their widespread usage in daily life, unique properties, and rapid development in the field of nanotechnology. Regarding their usage in various fields, it is suggested that soil is the final environmental sink for NPs. Nanoparticles with excessive reactivity and deliverability may be carried out as amendments to enhance soil quality, mitigate soil contaminations, make certain secure land-software of the traditional change substances and enhance soil erosion control. Meanwhile, there's no record on the usage of Nano superior substances for mine soil reclamation. In this study, five soil specimens have been tested at 4 sites inside the region of mine (<100 m) to study zeolites, and iron sulfide nanoparticles. Also, through using Artificial Neural Network (ANN) and Extreme Learning Machine (ELM), this study has tried to appropriately estimate the mechanical properties of soil under the effect of these Nano particles. Considering the RMSE and R2 values, Zeolite Nano materials could enhance the mine soil fine through increasing the clay-silt fractions, increasing the water holding capacity, removing toxins and improving nutrient levels. Also, adding iron sulfide minerals to the soils would possibly exacerbate the soil acidity problems at a mining site.

• 핵의학기술
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• 제13권3호
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• pp.143-146
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• 2009

Purpose: We use the centrifugation of refrigeration state in separation of blood serum, Anti-ds-DNA, Vitamin $B_{12}$/Folate and GAD-Ab assay. However, Cortisol urine and 25-Hydroxyvitamin $D_3$ ($25OHD_3$) are conducted centrifuge at room temperature. This is troublesome that change centrifugation temperature into room temperature due to using of most assays at cold temperature. Therefore when using centrifuge after extraction of Cortisol urine and $25OHD_3$, we conducted researches on effect of the centrifugation temperature in assay results. Materials and Methods: In Cortisol urine, add dichloromethane 1.0 mL in urine $500\;{\mu}L$, mix for 15 minutes, and then centrifuge for 8 minutes at 2600rpm. In $25OHD_3$ add acetonitrile 0.5 mL in serum $200\;{\mu}L$, and then centrifuge for 8 minutes at 2600rpm. Those experiments were conducted centrifuge at room temperature and $4^{\circ}C$. And experiments conducted immediately after centrifugation at $4^{\circ}C$ and standing for 20 minutes after centrifugation $4^{\circ}C$. Results: In Cortisol urine, room temperature result in 1.93, 2.18, 2.43, 9.45, 14.2 (${\mu}g/dL$). Experiments of performing immediately after centrifuge at $4^{\circ}C$ result in 1.8, 2.0, 2.3, 8.1, 13.7 (${\mu}g/dL$). Experiments of performing after 20 minutes result in 2.1, 2.1, 2.7, 9.95, 14.35 (${\mu}g/dL$). On the other hand, the $25OHD_3$ tests conducted at room temperature result in 7.13, 26.6, 35.8, 48.2, 74.8 (ng/dL). Experiments were conducted immediately by pipetting after $4^{\circ}C$ centrifugation result in 7.53, 30.9, 40.3, 61.5, 89.1 (ng/dL) as results are higher than experiments at room temperature. The experiments that conducted centrifuge at $4^{\circ}C$ and then left at room temperature for 20 minutes result in 7.40, 32.4, 41.3, 51.6, 85.6 (ng/dL). Conclusions: Experiments were conducted by using centrifuge at $4^{\circ}C$ are higher or lower than room temperature. The differences between results of standing for 20 minutes after centrifuge at $4^{\circ}C$ and those of centrifuge at room temperature are less than conducting immediately. It is concerned that experiments conducted immediately after centrifuge at $4^{\circ}C$ are incorrect, because tubes become dim due to temperature differences between $4^{\circ}C$ and room temperature. Therefore, it is desirable to centrifuge at room temperature as manual and we should pipet promptly without stopping.

• 한국식품위생안전성학회지
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• 제22권4호
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• pp.317-322
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• 2007

본 연구는 고흡습성 필름에 고추냉이 추출물을 첨가하여 제작한 항균흡습필름의 고등어 중 존재하는 식품위해 미생물에 대한 살균효과를 확인하고자 하였다. 총호기성균 및 식품위해미생물인, Escherichia coli O157:H7, Listeria monocytogenes Vibrio parahaemolyticus를 점 접종하여 항균흡습필름으로 포장한 후 저장온도, 기간별 및 항균 필름의 코팅 횟수가 균의 성장 및 사멸에 미치는 영향을 관찰하였다. $5^{\circ}C$에서 총균수, Escherichia coli O157:H7, Listeria monocytogenes의 성장 억제 효과는 $10^{\circ}C,\;15^{\circ}C$에서 보다 우수하였다. 특히 Usrio Vibrio parahaemolyticus는 $5^{\circ}C$에서 저온에 민감한 반응을 보이면서 모든 시료에서 1일, 4일 후 각각 약 $1\;log_{10}cfu/g\;and\;1.80\;log_{10}cfu/g$ 정도 감소하다가 7일 후에는 검출한계 아래로 모두 사멸하였다. 고추냉이 추출 물질이 함유된 흡습필름은 $10^{\circ}C,\;15^{\circ}C$에서 보다 $5^{\circ}C$ 에서 우수한 항균효과를 보였다. 세 가지 농도별 항균효과는 $5^{\circ}C$ 에서 두드러진 농도별 항균효과 차이를 보였으며 코팅 횟수가 늘어날수록 항균효과가 컸다. 이는 항균필름, 한 가지로만은 저장기간 향상에 한계가 있고 냉장저장이라는 hurdle을 동시에 적용하여 항미생물 synergy 효과를 보인다는 증거가 된다.

• 한국식품영양과학회지
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• 제15권3호
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• pp.286-293
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• 1986

본 연구에서는 엽채류(葉菜類)의 수송(輸送) 저장(貯藏)을 최적화(最適化)하기 위한 기초자(基礎資料)를 얻고자 엽채류중(葉菜類中)에서 조위현상(凋萎現象)이 쉽게 일어나고 년중(年中) 재배(裁培)가 가능한 시금치와 부추를 공시(供試), 자작(自作)한 Creep-tester를 사용하여 온도(溫度) $3{\sim}37^{\circ}C$ 습도(濕度) $70{\sim}95%$의 범위에서 조위(凋萎) 따른 물성변화(物性變化)를 측정(測定)한 결과 다음과 같은 결론(結論)을 얻었다. 1) 시료(試料)의 겉보기밀도는 조위도(凋萎度)가 클수록 증가(增加)했으며 특(特)히 시금치와 부추에서는 수분함량(水分舍星)이 각각(各各) 7%, 6.5%로 감소(減少)함에 따라 겉보기밀도가 70%, 53%로 크게 증가(增加)했다. 2. 파단응력(破斷應力)은 양(兩) 시료(試料) 모두 수분(水分)이 감소(減少)함에 따라 증가(增加)하는 경향(傾向)을 보였다. 3. 가학물성(力學物性)인 탄성율(彈性率)과 점성율(粘性率)은 수분함량(水分舍星)과 강한 상관관계(相關關係)를 나타냈다. 그러나 $3^{\circ}C$와 $37^{\circ}C$의 온도변화(溫度變化)에 따른 이들의 변화(變化)는 거의 나타나지 않았다. 4. 조위(凋萎)의 가역성(可逆性)에 대한 실험(實驗)에서는 양(兩) 시료(試料) 모두 외관(外觀), 수분함량(水分舍星) 및 탄성율(彈性率)은 원상(原狀)으로 복원(復元)되나 점성율(粘性率)은 약간저하(若干低下)했다. 5. 시료(試料)의 온도(溫度)에 따른 신축성(伸縮性情)에 대하여는 동일수분함양(同一水分含量)의 시료(試料)에 있어서 온도상승과정(溫度上昇過程)($3^{\circ}C{\to}37^{\circ}C$)에는 수축(收縮)하고 하강과정(下降過程)($37^{\circ}C{\to}3^{\circ}C$)에는 신장(伸長)하는 경향(傾向)을 나타냈다.

• 한국포장학회지
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• 제28권3호
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• pp.201-210
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• 2022

Expanded polystyrene (EPS) is the most commonly used fresh food refrigeration insulation in Korea and Europe. Moreover, as the use of disposable packaging materials has increased significantly along with non-face-to-face delivery services since the COVID-19 crisis, social issues related to waste disposal are also being raised. Therefore, in this study, the life cycle of EPS boxes for fresh food is focused on the factors that have a large difference between incineration and landfill including recycling in Europe and Korea in the disposal process after use, and raw materials and energy in the manufacturing process, which account for a large portion of the environmental impact value. We tried to compare the environmental impact of evaluation. Overall, the raw material production stage, box manufacturing stage, and packaging stage have similar processes in Europe and Korea, but unlike Europe, Korea, which lacks landfills and incineration facilities, has focused on expanding the recycling rate. It was necessary to do an environmental impact assessment. Data affecting the environment were derived based on 2019 and 2020 data for Korea and 2017 and 2020 data for Europe. In order to predict the future environmental impact assessment, assumptions about the disposal rate in 2025 and 2030 were introduced and evaluated. As a result of this study, it was found that the raw material production stage of EPS boxes, which have similar processes in both Korea and Europe, has the greatest effect on the global warming effect of Korean EPS boxes. However, Korea, which has a relatively high recycling rate in the disposal process compared to incineration and landfill, showed better environmental performance than Europe in most impact indicators except freshwater eutrophication. In particular, Korea has increased the overall recycling rate compared to Europe by replacing various recyclable materials such as building materials and sundries with XPS (extruded polystyrene) recycled materials. In conclusion, it was found that increasing the recycling rate rather than incinerating and landfilling EPS boxes for fresh food in the domestic EPS industry has relatively less environmental load compared to Europe.

• 대한본초학회지
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• 제32권4호
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• pp.25-32
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• 2017

Objectives : Chungsimyeonja-eum (CSYJE; Qingxinlianzi-yin in Chinese; Seishinrenshi-in in Japanese), a traditional herbal medicine, has been used for treating mouth dryness, hyperuresis. This study was designed to determine preservation period of CSYJE. We investigated the stability and biological activity of CSYJE depending on the preservation temperature and periods. Methods : CSYJE decoction was preserved for 0-6 or 12 months at room temperature (RT, $23{\pm}1^{\circ}C$) or refrigeration ($4^{\circ}C$). To evaluate the stability of CSYJE decoction, pH and dissolved solids content were measured. High-performance liquid chromatography (HPLC) analysis was performed to determine marker compounds-liquiritin apioside, liquiritin, baicalin, wogonoside, and glycyrrhizin-in CSYJE. To determine anti-inflammatory effect of CSYJE, prostaglandin $E_2$ ($PGE_2$) was measured in LPS-stimulated RAW 264.7 macrophages. Results : Both at RT and $4^{\circ}C$, pH was decreased depending on the preservation periods. There was no changes in dissolved solids content depending on the preservation temperature and periods. Both at RT and $4^{\circ}C$, the contents of liquiritin apioside and liquiritin were slightly increased at 1 month of storage. The level of baicalin was decreased time-dependently and the disappearance rate at RT is larger than at $4^{\circ}C$. CSYJE inhibited $PGE_2$ production in LPS-stimulated RAW 264.7 cells and maintained inhibitory effect by 12 months both at RT and $4^{\circ}C$. Conclusions : Based on the disappearance rate of the baicalin in CSYJE, the preservation period is recommended within 8 months for RT and 12 months for $4^{\circ}C$.

• 생물환경조절학회지
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• 제32권2호
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• pp.172-180
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• 2023

감자의 저장 한계기간을 결정하는 가장 주요한 요인은 병과 특히 맹아의 발생이다. 본 연구는 조·중생종 봄감자의 하계 저장기간 동안 고랭지 감자 재배단지에서 이용되고 있는 냉장 시스템이 없는 반지하 저장고에서 '대서', '수미', 그리고 '추백' 품종의 맹아 출현 시기를 확인하고, CIPC 처리 시 품종별 감자 괴경의 맹아억제 효과를 구명하고자 수행되었다. 본 연구는 농약 허용물질목록관리제도(PLS, positive list system)에서 규정한 처리농도보다 낮은 농도인 10mg와 20mg, 그리고 규정에 준하는 농도인 30mg의 CIPC가 감자 괴경 1kg에 도포되도록 처리 시 맹아 억제 효과를 보이는지 구명하였다. 본 실험에 이용된 토굴형 저장고는 내부 온도가 외기 온도보다 5℃ 이상 저하되었고, 특히 주야간 온도를 포함하여 실험기간 동안 최저와 최고 온도의 차이가 5℃ 정도로 외기온도 차이의 1/2 수준으로 줄였다. 품종별 감자의 맹아는 대조구에서 극조생종인 '추백'이 가장 빨라 저장 6주차에 50% 이상 맹아가 출현하였고 신장도 진행되었으며, '수미'는 저장 6주차에, '대서'는 저장 8주차에 각각 맹아가 출현하기 시작하였다. CIPC 처리 시 '대서'와 '수미'는 모든 처리구에서 맹아 출현이 억제되었다. '추백'은 7주차에 모든 처리구에서 맹아는 관찰되었으나 저장 8주차까지 괴경에서 맹아의 신장은 완전히 억제되었다. 휴면이 빨리 타파되는 극조생종인 '추백'을 제외하면 '대서'와 '수미'는 CIPC 처리 시 10mg·kg^-1의 저농도 처리로도 맹아억제 효과를 보이는 것으로 판단된다. 저장 중 지속적으로 감모가 발생하였으나 저장 8주차까지 0.7-1.6%의 낮은 감모율을 보였으며, 품종 또는 CIPC 처리에 따른 변화는 일정한 경향이 없었다. 품종별 및 CIPC 처리구별로 저장 중 육안으로 관찰되는 병리장해는 대부분 마른썩음병(건부병)이었으나 발병 개체는 많지 않았다. 감모율과 병 발생이 적었던 이유는 본 실험에 이용된 시료가 18℃와 RH 90%에서 10일간 큐어링 처리한 후 육안 선별한 건전한 괴경이었으며, 저장고에 냉장시스템이 없어 대류현상이 발생하지 않아 무게감소와 병원균의 확산이 억제되었기 때문으로 사료된다.